The relative importance of various factors influencing the prognosis and survival in the treatment of thymoma is still controversial. Sixty five patients operated on for thymoma from Jan. 1981 to Dec. 1994 were evaluated, 28 patients(43.1%) with
myasthenia gravis and 37 patients(56.9%) without. Masaoka staging revealed stage Idisease in 28 patients(43.1%), stage II in 13 patients(20.0%), stage III in 22 patients(33.8%), stage Iva in l patients (1.5%), and stage IVb in l patient(1.5%).
There was
no operative mortality. A complete resection was performed in 48 patients(73.8%)patients, associated in 10 patients (15.4%) with postoperative adjuvant treatment(radiotherapy 5; chemotherapy 1; radio-and chemotherapy 4). Thymomas were found to be
predominantly of the epithelial type in 16 patients(24.6%), predominantly lymphocytic type in 18 patients(27.7%), and mixed in 22 patients(33.9%). The overall 5-and 10-year survival rates were 87% and 82%, respectively. Factors indicating a poor
prognosis included local invasion, incomplete excision, thymic carcinoma, advanced staging and myasthenia gravis. The degree of tumor invasion turned out to be the main prognostic factor, and treatment should be planned accordingly. The prognosis
is
best predicted by the stage of the tumor as determined intraoperatively and is poorer in patients with incomplete resection than in those with complete resection of the thymoma. No recurrence developed in patients with stage I disease.
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